[NNTP] LIST EXTENSIONS and an NNTPv2 capability

[Clive D.W. Feather]

Ken Murchison said:
> I'd submit that LIST EXTENSIONS is no longer an optional command for the 
> server.  Any server compliant with with RFC 977bis MUST implement LIST 
> EXTENSIONS

Agreed. Or my proposed STATUS command.

> and MUST advertise at least the NNTPv2 capability, even if no 
> extensions are implemented.  This serves to tell the client that 
> previously optional/non-standard commands that we have standardized as 
> part of the base specification (e.g. DATE) are supported.

This is the versioning issue I discuss in my other message.

> First, I think that the base doc and/or any extension docs have to make 
> it clear that if a NNTPv2 server implements an extension it MUST 
> advertise the appropriate extension label via LIST EXTENSIONS.

Agreed.

> As far as the legacy extensions which we are standardizing, we need to 
> document somewhere that any server which supports one or more of these 
> extensions and is upgraded to be compliant with RFC 977bis MUST also be 
> upgraded to be compliant with the standardized versions of these 
> extensions (including advertising it where appropriate).

Or indicate that they're providing pre-standard versions. Again, I've shown
how to do this in my proposal.

> Unfortunately, I don't know where this should be documented.  I don't 
> think we can put it in the base doc since we don't want the base doc 
> referencing extension docs.  Putting it in the extensions docs doesn't 
> really help because a server author may fail to reference them when 
> upgrading to RFC 977bis compliance.

We can't force someone to upgrade their support of an extension. All they
have to do is declare it to be a private extension whose commands happen to
have the same name. Better to recognise this than to pretend it doesn't
happen. There's a similar issue with transition from one version of a
specification to the next one; both of these are addressed in my STATUS
proposal.

[I realize this sounds a bit like "STATUS solves everything" boasting, but
it isn't; the issues in this thread drove a lot of my design.]

-- 
Clive D.W. Feather  | Work:  <clive at demon.net>   | Tel:    +44 20 8495 6138
Internet Expert     | Home:  <clive at davros.org>  | Fax:    +44 870 051 9937
Demon Internet      | WWW: http://www.davros.org | Mobile: +44 7973 377646
Thus plc            |                            |